package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import io.netty.util.internal.StringUtil;
import lombok.val;
import org.springframework.data.geo.*;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    // 通过id查询商户
    @Override
    public Result queryById(Long id) throws InterruptedException {
        // 1.缓存穿透
//        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);
        // 2.互斥锁解决缓存击穿
//        Shop shop = queryWithMutex(id);
        // 3.逻辑过期解决缓存击穿
       Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        if (shop == null){
            return Result.fail("店铺不存在！");
        }
        // 7.返回
        return Result.ok(shop);

    }

    /*
    缓存穿透
     */
    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            // 3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson,Shop.class);
            return shop;
        }
        // 判断命中的是否是空值
        if(shopJson != null){
            // 返回错误信息
            return null;
        }
        // 4.不存在，根据id查询数据库
        Shop shop = getById(id);
        // 5.不存在，返回错误
        if(shop == null){
            // 将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            // 返回错误
            return null;
        }
        // 6.存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 7.返回
        return shop;
    }

    /*
    互斥锁解决缓存击穿
     */
    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            // 3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson,Shop.class);
            return shop;
        }
        // 判断命中的是否是空值
        if(shopJson != null){
            // 返回错误信息
            return null;
        }
        // 4.实现缓存重构
        // 4.1 获取互斥锁
        String lockKey = "lock:shop:" + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            // 4.2 判断是否获取成功
            if(!isLock){
                // 4.3 失败，则休眠重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }

            // 4.4 成功，根据id查询数据库
            shop = getById(id);
            // 模拟重建的延时
            Thread.sleep(200);
            // 5.不存在，返回错误
            if(shop == null){
                // 将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                // 返回错误
                return null;
            }
            // 6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            // 7.释放互斥锁
            unLock(lockKey);
        }
        // 8.返回
        return shop;
    }

    /*
    逻辑过期解决缓存击穿
     */
    public Shop queryWithLogicalExpire(Long id) throws InterruptedException {
        String key = CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        Thread.sleep(200);
        // 2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            // 3.不存在，返回空值
            return null;
        }
        // 4.存在，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        // 5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            // 5.1未过期，返回店铺信息
            return shop;
        }
        // 5.2已过期，需要缓存重建
        // 6.缓存重建
        // 6.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        // 6.2是否获取锁成功
        if (tryLock(lockKey)) {
            if (expireTime.isBefore(LocalDateTime.now())) {
                // 6.3成功，判断缓存是否过期，若过期，开启独立线程，实现缓存重建
                CACHE_REBUILD_EXECUTOR.submit(() ->{
                    try {
                        // 重建缓存
                        this.saveShop2Redis(id,20L);
                    } catch (Exception e) {
                        throw new RuntimeException(e);
                    }
                    finally {
                        // 释放锁
                        unLock(lockKey);
                    }
                });
            }
        }
        // 6.4返回商铺信息
        return shop;
    }

    /*
    带着逻辑过期时间写入Redis
     */
    public void saveShop2Redis(Long id,Long expireSeconds){
        // 1.查询店铺数据
        Shop shop = getById(id);
        // 2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        // 3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }


    // 获取锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    // 释放锁
    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }


    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id == null){
            return Result.fail("店铺id不能为空");
        }
        // 1. 更新数据库
        updateById(shop);
        // 2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if(x == null || y == null){
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query().
                    eq("type_id",typeId).
                    page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        // 3.查询redis、按照距离排序、分页
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().radius(
                key,
                new Circle(new Point(x, y), new Distance(5000)),
                RedisGeoCommands.GeoRadiusCommandArgs.newGeoRadiusArgs()
                        .includeDistance()  // 包含距离信息
                        .limit(end)
        );
        // 4.解析id
        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if(list.size() <= from){
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1 截取from - end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String ,Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD (id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }
}
